This invention relates to an intake sound generator for a vehicle engine.
In most automobiles, there is a general desire to reduce the levels of noise in the vehicle cabin, which can be distracting or tiring for the driver and other occupants. Sources of noise include road noise generated between the tyres and the road, wind noise generated by the movement of the automobile through the air, and engine noise generated by the engine and its associated moving parts. The sound level of these sources of noise in the cabin of an automobile can be lowered through the use of soundproofing and isolating materials between the components of the cabin and the vehicle chassis.
However, there are occasions when a driver will want better aural feedback from the engine whilst maintaining low levels of road and wind noise. For example, on a track the driver of a sports car looking to push the car to its limits of performance will want as much feedback as possible, including aural feedback from the engine. This helps the driver to, amongst other things, optimally time gear changes. If the noise levels in the cabin of the sports car have been overly reduced through the use of soundproofing, the aural feedback received by the driver can be significantly diminished.
In order to address this problem and to improve the acoustic feedback from turbocharged and supercharged engines, intake sound generators have been proposed such as the Mann+Hummel Symposer™. The Symposer is essentially an arrangement of diaphragms and tubes which transfers engine-generated pulsations directly into the passenger compartment. A Symposer is connected directly before an engine throttle on the intake path of an engine so as to accurately pick up the variations in engine charge and convey these to the driver. This can help to overcome the acoustic dampening effect of the compression developed by turbochargers and superchargers in an air intake system and more generally helps useful acoustic components generated at an engine to bypass any soundproofing in the vehicle.
However, with most automobiles now having sophisticated electronic engine management systems, the position of an engine throttle depends on many different factors and can seem to be removed from the accelerations and decelerations of the vehicle intended by the driver. As a result, the feedback received by a driver from a Symposer can be confusing and unhelpful.
There is therefore a need for an improved intake sound generator for providing aural feedback to a driver.